Method of producing polymers of trioxane and similar oxacompounds



United States Patent ABSTRACT OF THE DISCLOSURE Cyclic oxa-compoundssuch as epichlorohydrin, trioxane, dioxolane, tetrahyrofuran,oxacyclobutane, ethylene oxide, and cyclic derivatives thereof, arepolymerized at temperatures up to about 150 C. in the presence of acatalytic quantity of an organo silicon compound of the formula:

R2 lat-sh A wherein R may be hydrogen, alkyl or a siloxane chain of thegeneral formula:

wherein n is an integer between 0 and 100, each of R and R is CH;,, C Hor CH =CH-, and Ac is the anion of a strong acid. Some of the polymershave good emulsifying properties.

The present application is a continuation-in-part of our copendingapplication Ser. No. 266,173, filed Mar. 19, 1963, and now abandoned andentitled, Process for the Production of Polymers of Trioxane and SimilarCyclic Oxa-Compounds.

Background of the invention The present invention relates to theproduction of polymers of trioxane and similar oxa-compounds such asdioxolane, tetrahydrofuran, oxacyclobutane, ethylene oxide and theirderivatives by cationic polymerization.

In polymerization and copolymerization of substances of this type, useis made of B1 and its complexes with organic substances such as phenols,acids, ethers, esters, ket-ones or aldehydes and also other Lewis acidssuch as e.g. BCI ZnCl CdCl AlCl AlB1' SnCl SbCl TiCl FeCl BiF AiF TiFetc.

As initiators these are used either alone or in combination withcocatalysts. In addition to these initiators the use of strong inorganicacids such as H 80 HClO, etc. is also known.

It is usually difficult to remove from the polymer residual catalyst ofthe type described above. Washing with water may result in partialhydrolysis of the catalyst yielding insoluble or sparingly solublehydroxy compounds which remain in the polymer and substantially reduceits stability. The use of organic solvents for washing the polymer isexpensive and does not permit of an economical production.

Also the measuring out of such catalyst for use presents difiiculties.Such catalysts are usually pooriy soluble in organic solvents; moreover,solvents suitable for the pur- "ice poses of cationic polymerization areavailable only in a fairly restricted choice. Good solvents for saidcatalysts are found e.g. among halogenated hydrocarbons which. however,can be used in a few instances only in cationic polymerization owing totheir high transfer ability. The transfer reaction of a growing polymerchain with a molecule of a halogenated solvent lowers the molecularWeight of the polymer and results in the chemical incorporation of thehalogen atom in the polymer. Halogen-containing polymers display adecreased stability as a function of time, which can be explained by thefact that they decompose into halogen acids which catalyze thedecomposition of the polymer. The incorporation of a halogen atom intothe polymer chain just described may also be the result of a reactionwith the catalyst.

Summary of the invention According to the present invention, thepolymerization of at least one cyclic oxa-compound which may be andusually is, selected from the group consisting of epichlorohydrin,trioxane, dioxolane, teltrahydrofuran, oxacyclobutane, ethylene oxide,and cyclic derivatives thereof, is carried out by polymerizing thecyclic oxa-compound between 20150 in the presence of a catalyticquantity of an organo silicon compound having the following formula:

R2 nr-sl d AC a wherein R is hydrogen, CH C H or a siloxane chain of thegeneral formula wherein n is an integer between 0 and 100, each of R andR is CH;,, C H or CH =CH-, and Ac is the anion of a strong acid.

Description of the preferred embodiments According to the presentinvention, the polymerization is achieved by means of complexes oforgano-silicon compounds with strong acids of the general formulawherein R is a hydrogen atom, CH C H or a siloxane chain of the generalformula wherein n has a value between 0 and R and R are CH C H or CH=CH- and Ac is the anion of the used strong acid such as, e.g., SO H C10etc.

R and R in theory, may be also aryls. Aryls substituted at the Si atomare not stable in acid medium and split off. The initiator so formed isquite efiicient but possesses an increased number of active spots in themolecule and reacts in a kinetically complex manner.

By the use of said initiator in the polymerization of oxygen-containingheterocycles and their derivatives, the cation forming theorganosil-icon complex is incorporated as one end group of the polymerchain; this complex is stable and therefore cannot be the source ofreactions rupturing the chain. The other end group of the polymer chainis formed by the anion of the acid if the polymerization was carried outin a pure system. This anion is comparatively easy to deactivate bywashing with water.

The preparation of this initiator is very simple. It con sists in thereaction of some of the usual polycyclosiloxanes with (practically)anhydrous acid at room temperature. The kind of the acid used determinesthe length of the siloxane chain It and thereby also its solubility inorganic solvents.

Hexaalkyldisiloxane can he added to polycyclosiloxane in order toinfluence the quality and the character of R of the catalyst.

It is one of the advantages of this initiator that it containspractically no water, as all moisture (including any water ofcondensation) settles down and can very easily be removed from theinitiator.

The following examples are given as illustrative only, without limitingthe invention to the specific details thereof.

EXAMPLE I 35 g. of trioxane containing less than 30 p.p.m. of H 0, lessthan p.p.m. of HCOOH and less than 5 p.p.m. of CH OH, and in which nomethylal was found by chromatographic means was polymerized at 85 C.using 0.1 millimoles of an organo-silicon complex of the type Me Me CH3-sio]si rrsot Me 6-8 Me dissolved in 1 ml. of methylcyclohexane.

The initiator was prepared by reacting 98% H 80 withoctamethylcyclohexasiloxane in the presence of hexamethyl-disiloxane(the weight ratios were 1:4:2) at room temperature with occasionalstirring. The reaction lasted for 24 hours. After separating the waterof condensation, the content of the effective substanceviz. the acid-wasdetermined by acidimetric titration. The initiator was dissolved inmethylcyclohexane to yield a solution of a concentration as indicated.

The polymerization was interrupted after 65 minutes when the conversionreached 30 percent. The polymer was washed with hot water andsubsequently dried in air.

The polymer had the following properties and characteristics: Reducedviscosity 0.98 dl./ g. (polymer concentration was 0.2 g./100 ml. ofsolvent which was a 3 :1 mixture by weight of tetrachloroethane andphenol, the temperature of measurement was 90 C.). The stable portion(defined as that portion of the polymer which remains after refluxingthe polymer with 0.1 percent alcoholic KOH for 3 hrs.) was 25 percent;the initial rate of decomposition at 222 C. was 1.02 percent per minute(determined by means of thermal balance operated in air).

EXAMPLE II 30 g. of trioxane containing less than 30 p.p.m. of H 0, lessthan 5 p.p.m. of HCOOH, less than 5 p.p.m. of MeOH and less than 50p.p.m. of methylal was copolymerized with 5 g. of dioxolane using 0.08millimole of the catalyst as described in Example I at a temperature of80 C. in a dilatometer which is provided with means for automaticallyrecording the course of polymerization. Polymerization was interruptedafter 2 hrs. at a conversion of 15 percent. The polymer was washed withhot water and dried in air. The polymer had the followingcharacteristics (defined as in Example I): reduced viscosity-l.02dl./g., stable portion98 percent, initial rate of decomposition at 185C.0.l percent per minute.

EXAMPLE III 50 g. of dioxalane was polymerized at 65 C. using Oilmillimole of the organo-silicon complex which was obtained through bulkpolymerization of parts by weight of octamethyltetracyclosiloxane and 1part by weight of sulfuric acid. The reaction took place as in Example Iat room temperature with occasional stirring for '24 hours. Aftercentrifugation, the upper phase containing the acid complex wasseparated and dissolved in methylcyclohexane. The solution of theinitiator substance Bite Lite 11- OSi -o-si r-rsot Me 10-12 Me wasanalyzed for the content of the Si+HSO ion pairs and the necessaryamount of the solution was measured out to initiate the polymerization.Polymerization was interrupted at a 30 percent conversion. Afterneutralizing the catalyst with alcoholic KOH, the polymer wasprecipitated from the ternary mixture H O-alcohol-cyclohexane. Thepolymer so obtained had a reduced viscosity of 0.25 dL/ g. The polymerwas soluble in water and has good emulsifying properties.

EXAMPLE IV ml. of epichlorohydrin was polymerized with 0.3 millimoles ofthe organo-silicon complex described in Example 1. During polymerizationwhich lasted 2 /2 hours the reaction mixture was cooled intensely to 35C. After this time the catalyst was removed by repeated shaking withwater. The polymer was freed from unreacted epichlorohydrin and water byevacuating it for 48 hours at a temperature of 40 C. The polymer, had alow molecular weight, and was a viscous liquid, stable at C. anddisplaying interesting properties; it has a good gelatinizing actiontoward polyvinyl chloride from which it does not migrate even after afortnights standing at 48 C.

EXAMPLE V 0.4 millimoles of the catalyst described in Example 3 wasdissolved in 50 ml. of methylcyclohexane contained in a closed vessel.30 g. of ethylene oxide was introduced by bubbling gaseous ethyleneoxide from a pressure vessel into this solution. Before entering thereaction vessel, which was maintained at 25 C., the ethylene oxide wasdried using a 5 molecular sieve. The polymerization was interrupted byinjecting 10 m1. of gaseous ammonia into the reactor. The polymer wasisolated by evacuating the reaction mixture. 21 g. of polymer wasobtained which was stable at higher temperatures and had a molecularweight of 5,000.

EXAMPLE VI Preparation of the initiator: 1 part by weight of anhydrousHClO was added to 10 parts by weight oftetramethyltetravinylcyclohexasiloxane. After 5 hours the reactionyielded a 1ow-viscosity polymer. Excess acid was removed bysedimentation in a separatory funnel, the siloxane layer was dissolvedin cyclohexane and after analysis for the content of Si+ClO the requiredamount (5 ml.) was added to the monomer. The initiator had the followingcomposition:

Me on=orn Mo H- OSi0' o-si 010.-

Mo cn=om 4 Me 30 g. of trioxane of analytical data as in Example II waspolymerized at 80 C. in a reactor in which an excess pressure (90 mm.Hg) of ethylene oxide was maintained. Polymerization was catalyzed by0.08 millimoles of the organo-silicon complex as in Example I. Theprocess was interrupted at a 10 percent conversion by pouring thereaction mixture into water having a temperature of 80 C. The polymerwas washed with hot water until negative in reaction for formaldehydeand dried in an air oven at 60 C. to constant weight. The polymer hadthe following characteristics (defined as in Example 1): the reducedviscosity was 0.98 dl./g., stable portion was 96 percent, initialdecomposition rate was 0.12 percent per minute at 222 C. In allforegoing examples an inert organic solvent e.g. cyclohexane can also beused as the medium in which the polymerization takes place and theobtained polymers have similar properties as those obtained by theprocess described in the examples.

EXAMPLE VIII The initiator was prepared by a procedure exactly similarto that of Example III, except that octaethylcyclo- 'hexasiloxane wasused instead of octamethylcyclohexasiloxane. The initiator so producedwas more soluble in hydrocarbon solvents. Other properties, was well asthe properties of the polymer produced by its action, were the same asin Example III.

EXAMPLE IX Preparation of the initiator: 1 part by weight of anhydrousHClO was added to 50 parts by weight of octamethylcyclotetrasiloxane.After 24 hours of reaction at room temperature the unreacted acid wasseparated from the upper viscous layer of the polymer containing the SiClO complex; the polymer was dissolved in cyclohexane. The active partof the initiator, viz.

so Me Me was used to initiate the polymerization of tetrahydrofuran. 0.5mole of Si ClO was used to initiate the polymerization of 30 moles oftetrahydrofuran at C. The polymer formed had the character of a blockcopolymer made up of siloxane and tetrahydrofuran sections and was notedfor its hydrophobous qualities.

EXAMPLE X Initiator prepared as in Example VI except thatdecamethylcyclopentasiloxane was used instead oftetramethyltetravinylcyclotetrasiloxane, to polymerize 3,3bischloromethyloxacyclobutane. 0.1 mole/kg. of complex Si ClO; initiatedat 0 C. the polymerization of 75 volume parts of 3,3bischloromethyloxacyclobutane in 25 volume parts of heptene. After fivehours of polymerization the reaction was stopped by introducing 0.5mole/kg. of ammonia into the reaction medium; the polymer was separatedand washed. After washing twice in boiling water the polymer did notcontain any detectable traces of acids.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

We claim:

1. A process for the polymerization of at least one cyclic oxa-compoundselected from the group consisting of epichlorohydrin, trioxane,dioxolane, tetrahydrofuran, oxacyclobutane, ethylene oxide, and cyclicderivatives thereof, which comprises polymerizing said cyclicoxacompound between 20-150 C. in the presence of a catalytic quantity ofan organo silicon compound having the following formula:

2 rat-S 6 AC6 wherein R is hydrogen, CH C H or a siloxane chain of thegeneral formula:

wherein n is an integer between 0 and 100, each of R and R is CH C H orCH =CH and Ac is the anion of a strong acid.

2. Process according to claim 1, wherein said organosilicon compound isused in an amount of from 0.1 to 500 millimoles per rnole of said cycliccompound.

3. Process according to claim 1, which comprises effecting said reactionin the presence of a solvent.

4. Process according to claim 1, which comprises effecting said reactionin the absence of a solvent.

5. Process according to claim 1, wherein said acid anion is SO H 6.Process according to claim 1, wherein said acid anion is C10 7. Processaccording to claim 1, wherein said cyclic compound is selected from thegroup consisting of trioxane and dioxolane and said org-ano-siliconcompound is 8. Process according to claim 1, wherein said cycliccompounds are selected from the group consisting of trioxane, dioxolaneand 3,3 bischloromethyloxacyclobutane, and said organo-silicon compoundis 9. Process according to claim 1, wherein said cyclic compound isselected from the group consisting of dioxolane and3,3-bischloromethyloxacyclobutane, and said organo-silicon compound iswherein n is an integer between 1 and 100, both inclusive, Me is methyl,and which has been obtained 'by bulk polymenization ofoct-amethylcyclotetrasiloxane with H 10. Process according to claim 1,wherein said cyclic compound is epic-hlorohydrin and said organo-siliconcompound is A to hle M si o-si rrsoi Me Me 11. Process according toclaim 1, wherein said cyclic compound is ethylene oxide and saidorgano-silicon compound is wherein n is an integer between 1 and 100,both inclusive. 13. Process according to claim 1, wherein said cycliccompounds are selected from the group consisting of triox'ane, ethyleneoxide, and/ or dioxolane.

14. The product obtained by the process of claim 1.

References Cited UNITED STATES PATENTS 7/1958 Mika 260448.2 1/1967Miller.

WILLIAM H. SHORT, Primary Examiner.

T. PERTILLA, Assistant Examiner.

